The media is a pervasive institutional structure in all modern societies. It has often been argued that the media industry encourages unsafe sex by irresponsibly portraying sexual behaviors. As a result, it is widely claimed that youth are negatively influenced by what they see, hear, and read in the media. There is, however, very little evidence to either support or refute this hypothesis. Historically, sexual portrayals in the media, like violence, have raised the ire of advocates, policymakers, and parents dating back to the first mass media marketed to children. Today, the issue remains an important agenda item and has led to public health policy interventions such as V-chip ratings and technology legislation, movie ratings, and video game advisories. Yet few studies of the "effects" of mass media on specific behaviors are done due to theoretical, logistic, design, and cost considerations. One specific reason for this is that much "media influence" is designed to shape and perpetuate consumer preferences and is therefore not targeted to behaviorally-defined groups but rather to the mass consumer public. But other kinds of media effects predicated on the principles of social learning theory and other theories can be predicted for specific "audiences" and specific behaviors. This application focuses on the media's role in presenting sexual content, implying sexual norms, modeling sexual decision making ("self-efficacy"), and displaying the outcomes of sexual behaviors in relation to young adolescents, a group whose attitudes, norms, self-efficacy, and decision-making skills are all in flux and development. This five-year research project is the first to combine behavioral theory, communication theory, and a state of the art content analytic approach to investigate the relationship between exposure to sex in the media and early initiation of sexual intercourse and other sexual behaviors. Using this approach, we develop both objective (i.e., content analytic) and subjective, theory-based measures of (a) the quantity and content of adolescent's exposure to sexual media and (b) adolescents' sexual behavior and its underlying psychosocial determinants (i.e. beliefs, attitudes, norms, self-efficacy and intention). These measures will be tested for their reliability and validity, and they will take developmental, gender and ethnic differences into account. Based on this formative research, we propose a three-wave longitudinal proof of concept study to investigate the empirical link between exposure to sexual content in a broad variety of media (i.e., television, movies, music CDs, the Internet, video games, and magazines) and sexual behavior. In summary, this research uses a theoretically grounded, methodologically sound approach to more fully examine the relationships between media exposure and AIDS-related sexual behavior.